CONTROL METHOD FOR CALIBRATING AN ACTUATION OF A CONVERTER LOCK-UP CLUTCH OF A HYDRODYNAMIC TORQUE CONVERTER

Abstract

A method for calibrating an actuation of a converter lock-up clutch of a hydrodynamic torque converter having a pump wheel and a turbine wheel connected to a power-split transmission. The transmission has at least two clutches each connected to a respective power-split shaft assembly and each configured be actuated separately to close and open in order to apply a clutch torque to the turbine wheel so that a rotation speed difference between the pump wheel and the turbine wheel changes. The method includes opening the converter lock-up clutch and the at least two clutches each connected to a respective power-split shaft assembly of the transmission, rotating the pump wheel with a specified rotation speed, and applying a clutch torque to the turbine wheel as a function of an actual rotation speed difference. Clutches connected to a different respective power-split shaft assembly of the transmission are actuated in the closing direction.

Claims

1. Control method for calibrating an actuation of a converter lock-up clutch (22) of a hydrodynamic torque converter (14) with a pump wheel (18) and a turbine wheel (20), which is connected to a power-split transmission (16), wherein the transmission (16) comprises at least two clutches (32, 34, 36) each associated with a respective power-split shaft assembly (26, 28, 30), which clutches can be actuated separately to close and open in order to apply a clutch torque (M.sub.K) to the turbine wheel (20) so that a rotation speed difference (Δn) between the pump wheel (18) and the turbine wheel (20) changes, the said method comprising the steps: opening (S1) the converter lock-up clutch (22) and the at least two clutches (32, 34, 36) each associated with a respective power-split shaft assembly (26, 28, 30) of the transmission (16), wherein the at least two clutches are configured to apply a clutch torque (M.sub.K) to the turbine wheel (20); rotating (S2) the pump wheel (18) at a specified rotation speed (n); and applying (S3) a clutch torque (M.sub.K) to the turbine wheel (20) as a function of an actual rotation speed difference (Δn.sub.IST) in order to reach a specified set-point rotation speed difference (Δn.sub.SOLL), wherein at least two clutches (32, 34), each associated with a respective power-split shaft assembly (26, 28) of the transmission (16), are actuated to close.

2. The control method according to claim 1, wherein before the applying (S3) of the clutch torque (M.sub.K) to the turbine wheel (20), the specified set-point rotation speed difference (Δn.sub.SOLL) is divided into at least two ranges (Δn.sub.1 -Δn.sub.n), and in two of the at least two ranges (Δn.sub.1; Δn.sub.2) a different number of the at least two clutches (32, 34, 36) is actuated in a closing direction in order to reach the specified set-point rotation speed difference (Δn.sub.SOLL).

3. The control method according to claim 2, wherein the number of ranges (Δn.sub.1 - Δn.sub.n) into which the specified set-point rotation speed difference (Δn.sub.SOLL) is divided, is smaller than or equal to a number of clutches (32, 34, 36) that can be actuated separately in order to reach the specified set-point rotation speed difference (Δn.sub.SOLL).

4. The control method according to claim 3, further comprising increasing the actual rotation speed difference (Δn.sub.IST) from the first (Δn.sub.1) to the n-th (Δn.sub.n) range,the actual rotation speed difference being limited by the set-point rotation speed difference (Δn.sub.SOLL), by correspondingly actuating in the closing direction an increasing number of the at least two clutches (32, 34, 36) which can be actuated separately in order to reach the specified set-point rotation speed difference (Δn.sub.SOLL).

5. The control method according to further comprising, at least in one (Δn.sub.n) of the ranges (Δn.sub.1 - Δn.sub.n), actuating, in the closing direction, each of the clutches that can be actuated separately in order to reach the specified set-point rotation speed difference (Δn.sub.SOLL).

6. The control method according to claim 2. further comprising at least in the range (Δn.sub.n) which is closest to the set-point rotation speed difference (Δn.sub.SOLL), actuating in the closing direction each of the clutches (32, 34, 36) that can be actuated in order to reach the specified set-point rotation speed difference (Δn.sub.SOLL) .

7. The control method according to claim 2, further comprising at least in the range (Δn.sub.1) that is farthest away from the set-point rotation speed difference (Δn.sub.SOLL), actuating in the closing direction one (32) of the clutches (32, 34, 36) that can be actuated in order to reach the specified set-point rotation speed difference (Δn.sub.SOLL).

8. A control unit (12) for carrying out a control method according to claim 1, wherein the control unit (12) comprises the following: a signal input (24) for receiving an input signal from a detection device for determining an actual rotation speed difference (Δn.sub.IST) between the pump wheel (18) and the turbine wheel (20); a signal output (38) for emitting an output signal that contains actuation commands for closing at least two clutches (32, 34); and a computer unit (40) which is connected to the signal input (24) and to the signal output (38) and is configured, on a basis of an input signal, to generate an output signal as a function of the actual rotation speed difference (Δn.sub.IST).

9. A transmission device (10) with a control unit (12) according to claim 8, wherein the transmission device comprises: a hydrodynamic torque converter (14) with a converter lock-up clutch (22), wherein the hydrodynamic torque converter (14) comprises a pump wheel (18) and a turbine wheel (20); and a power-split transmission (16) connected to the turbine wheel (20), wherein the power-split transmission (16) contains at least two clutches (32, 34, 36) each associated with a respective power-split shaft assembly (26, 28, 30), each of the at least two clutches being separately controllably connected to the signal output (38) of the control unit (12) so that each of the at least two clutches can be closed and opened, in order to apply a clutch torque (M.sub.K) to the turbine wheel (20), in such manner that an actual rotation speed difference (Δ.sub.IST) between the pump wheel (18) and the turbine wheel (20) changes.

10. A vehicle with the transmission device (10) according to claim 9. wherein the transmission device is configured for transmitting a drive force from a drive device for the propulsion of the vehicle.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0038] FIG. 1: shows a transmission device comprising a hydrodynamic torque converter with a converter lock-up clutch and a power-split transmission connected thereto.

[0039] FIG. 2: shows two control diagrams, one above the other, for a control method for the calibration of an actuation of the converter lock-up clutch of the hydrodynamic torque converter in FIG. 1.

DETAILED DESCRIPTION OF EMBODIMENTS

[0040] FIGS. 1 and 2 show an embodiment.

[0041] FIG. 1 shows a transmission device 10 with a control unit 12. The transmission device 10 is part of a vehicle (not shown) and is designed to transmit a driving force from a drive unit in order to propel the vehicle. The transmission device 10 comprises a hydrodynamic torque converter 14 and a power-split transmission 16.

[0042] The hydrodynamic torque converter 14 comprises a pump wheel 18 and a turbine wheel 20, and a converter lock-up clutch 22, which in this case can be actuated by a hydraulic disk clutch, and which has an internal pressure of up to 6 bar. The rotation speed difference An between the pump wheel 18 and the turbine wheel 20 can be determined by means of a determination device (not shown) connected to the control unit 12 for the direct or indirect determination of an actual rotation speed difference Δn.sub.IST. The hydrodynamic torque converter 14 is connected on its input side by way of the pump wheel 18 to the drive unit for propelling the vehicle and by way of the turbine wheel on its output side to the transmission 10. Thus, the rotation speed n of the pump wheel 18 corresponds to the output-side rotation speed n of the drive unit. Consequently, the rotation speed n of the pump wheel 18 can be taken to be the rotation speed n of the drive unit. The general mode of operation of such a hydrodynamic torque converter 14 with a converter lock-up clutch 22 is already known from the prior art.

[0043] The power-split transmission 16 is connected on its input side to the turbine wheel 20 and comprises three clutches 32, 34, 36, each associated with a respective power-split shaft assembly 26, 28, 30. The clutches 32, 34, 36 associated with a power-split shaft assembly 26, 28, 30 are clutches of the transmission 16 on the input side. The clutches 32, 34, 36 are connected to a signal output 38 of the control unit 12 and can be actuated separately to close and open them, in order to apply a clutch torque M.sub.K to the turbine wheel 20 so that the rotation speed difference Δn, i.e. the slippage between the pump wheel 18 and the turbine wheel 20 changes. In this case the clutch 32 is a clutch for forward driving (KV), the clutch 34 is a clutch for reverse driving (KR) and the clutch 36 is a further clutch (K4). If each of the clutches 32, 34, 36 associated with a power-split shaft assembly 26. 28, 30 is opened, then no clutch torque M.sub.K is applied to the turbine wheel 20.

[0044] The control unit 12 is designed to carry out a control method. For that purpose the control unit 12 comprises the signal input 24 for receiving an input signal, which transmits the actual rotation speed n.sub.IST-P of the pump wheel 18 and the actual rotation speed n.sub.IST-T of the turbine wheel 20 of the hydrodynamic torque converter 14. In addition, the control unit 12 comprises the signal output 38 for emitting an output signal, which transmits the actuation commands for the simultaneous closing of at least two of the clutches 32, 34, 36. Furthermore, the control unit 12 comprises a computer unit 40 which is connected to the signal input 24 and the signal output 38 and is designed, by virtue of an input signal, to calculate an actual rotation speed difference Δn.sub.IST between the pump wheel 18 and the turbine wheel 20 and to generate an output signal as a function of the calculated actual rotation speed difference Δn.sub.IST.

[0045] FIG. 2 shows two control diagrams, one above the other, for a control method for calibrating an actuation of the converter lock-up clutch 22 of the hydrodynamic torque converter 14 in FIG. 1. In both control diagrams the time t is plotted on the x-axis, wherein time points such as those marked as t.sub.0, t.sub.1, t.sub.2, t.sub.3, and t.sub.4 on one of the x-axes correspond to the equivalent time points on the other x-axis. On the y-axis the upper control diagram shows the respective clutch torques M.sub.K while the lower diagram shows the respective rotation speeds n.

[0046] The control method shown here is provided for large structural forms with correspondingly large manufacturing tolerances, and is carried out in the case of a stationary vehicle or a transmission correspondingly static on its output side during production, after an oil change or during the identification of inadequate shifting behavior, and comprises the following steps:

[0047] Step 1 (S1):

[0048] Opening of the converter lock-up clutch 22 and of the two clutches 32, 34 of the transmission 16, each respectively associated with a power-split shaft assembly 26, 28, which clutches are able to apply a clutch torque M.sub.K to the turbine wheel 20;

[0049] Step 2 (S2):

[0050] Rotating S2 the pump wheel 18 with a specified rotation speed n; and

[0051] Step 3 (S3):

[0052] Application S3 of a clutch torque M.sub.K to the turbine wheel 20 as a function of the actual rotation speed difference Δn.sub.IST in order to reach a specified set-point rotation speed difference Δn.sub.SOLL, wherein two clutches 32, 34, each respectively associated with a different power-split shaft assembly 26, 28 of the transmission 16, are actuated at the same time to close them.

[0053] The set-point rotation speed difference Δn.sub.SOLL is in this case specified in just the same way as the two equally large ranges Δn.sub.1, Δn.sub.2 into which the set-point rotation speed difference Δn.sub.SOLL is divided. Thus, both the first range Δn.sub.1 and the second range An.sub.2 each correspond to half the set-point rotation speed difference ½Δn.sub.SOLL.

[0054] The first range Δn.sub.1 extends from time-point t.sub.1 to time-point t.sub.2, during which the first clutch 32 is closed in order to apply an increasing clutch torque M.sub.K to the turbine wheel 20. Time-point t.sub.2 is reached when the actual rotation speed difference Δn.sub.IST has reached the top end of the first range Δn.sub.1 and thus at the same time the lower end of the second range Δn.sub.2 at the half rotation speed difference ½Δn.sub.SOLL. From that time-point t.sub.2 onward the clutch torque M.sub.K applied by the first clutch 32, i.e. the frictional performance of the clutch 32, is kept constant in that the first clutch 32 is not closed or opened any farther. Instead, now in addition the second clutch 34 is closed in order to increase the clutch torque M.sub.K on the turbine wheel 20 still more. In this case the time-point t.sub.3 is reached when the actual rotation speed difference Δn.sub.IST has reached the top end of the second range Δn.sub.2 at the set-point rotation speed difference Δn.sub.SOLL. From time-point t.sub.3 onward, the actual rotation speed difference Δn.sub.IST is adjusted to the set-point rotation speed difference Δn.sub.SOLL in that only and exclusively the first clutch 32 is actuated to close or open it. As soon as the set-point rotation speed difference Δn.sub.SOLL has been maintained over a defined time period and within a defined tolerance range, the time-point t.sub.4 has been reached. From this time-point t.sub.4 onward, in this condition a calibration process known from the prior art, for example calibration of the filling parameters of the converter lock-up clutch 22, is carried out in a subsequent Step 4 (S4). During this the converter lock-up clutch 22 is closed until a “touch point” is approached, at which the setpoint rotation speed difference Δn.sub.SOLL is no longer maintained. When during the course of a corresponding iterative search for the optimum filling parameters the fall of the set-point rotation speed difference Δn.sub.SOLL conforms to specified indicators, the filling is taken to be ideal.

[0055] By virtue of the division of the set-point rotation speed difference Δn.sub.SOLL into a number of ranges Δn.sub.1, Δn.sub.2, the Step 3 (S3) can be divided into the following part-steps:

[0056] Step 3.1 (S3.1):

[0057] Closing of the first clutch 32 in order to apply an increasing clutch torque M.sub.K to the turbine wheel 20, until the actual rotation speed difference Δn.sub.IST has reached half the set-point rotation speed difference ½Δn.sub.SOLL;

[0058] Step 3.2 (S3.2):

[0059] Closing the second clutch 34 in addition to the first clutch 32, in order to apply a still larger clutch torque M.sub.K to the turbine wheel 20, until the actual rotation speed difference Δn.sub.IST has reached the set-point rotation speed difference Δn.sub.SOLL;

[0060] Step 3.3 (S3.3):

[0061] Adjustment of the actual rotation speed difference Δn.sub.IST to the set-point rotation speed difference Δn.sub.SOLL, in that exclusively the first clutch 32 is actuated to close it or open it, until the set-point rotation speed difference Δn.sub.SOLL is maintained over a defined time period and within a defined tolerance range.

[0062] The condition reached in this way serves as the starting point for further steps, and thus in this case for the subsequent Step 4 (S4):

[0063] Step 4 (S4):

[0064] Calibration of filling parameters of the converter lock-up clutch 22.

[0065] Below further embodiments are described, which conform to the above-described basic principles.

[0066] According to a further embodiment it is provided that the closing process consists of an active or passive closing. In active closing the frictional performance of the clutch concerned is increased. In passive closing the frictional performance of the clutch concerned is kept constant, in that the clutch is kept closed. Correspondingly, according to a further embodiment it is provided that at least two clutches respectively associated with a different shaft assembly of the transmission are actuated in the closing direction at the same time. Opening refers to an active opening process in which the frictional performance of the clutch concerned is reduced.

[0067] According to a further embodiment it is provided that the transmission 16 comprises only two clutches 32, 34 associated with a power-split shaft assembly 26. 28 on the input side. In a further embodiment the transmission 16 comprises three - as described in the first embodiment - or more than three such clutches 32, 34, 36. In another embodiment the simultaneous closing of the at least two clutches 32, 34, 36, i.e. the clutch torque that results therefrom, is quantitatively the same or different.

[0068] According to a further embodiment it is provided that before a clutch torque M.sub.K is applied to the turbine wheel 20, the set-point rotation speed difference Δn.sub.SOLL is divided into at least two ranges Δn.sub.1 - Δn.sub.n as described in the first embodiment. According to a further embodiment, in two Δn.sub.1, Δn.sub.2 of the at least two ranges Δn.sub.1 - Δn.sub.n a different number of clutches 32, 34 is actuated in the closing direction in order to reach the specified set-point rotation speed difference Δn.sub.SOLL. In another embodiment a) the set-point rotation speed difference Δn.sub.SOLL, b) the number of ranges into which the set-point rotation speed difference Δn.sub.SOLL is divided, or c) the number of clutches actuated in each range Δn.sub.n is specified. According to a further embodiment two of the variables a), b), and c) are predetermined. In another embodiment all three variables a), b), and c) are predetermined.

[0069] According to a further embodiment the ranges Δn.sub.1 - Δn.sub.n are all the same size - as described in the first embodiment - or of different sizes. In a further embodiment the ranges Δn.sub.1 - Δn.sub.n become larger toward the set-point rotation speed difference Δn.sub.SOLL. In another embodiment the size of a range Δn.sub.n is adapted to the maximum clutch torque of the clutches respectively actuated in it. According to a further embodiment this adaptation takes place on the basis of the lowest maximum clutch torque M.sub.K of the clutches respectively actuated therein. The maximum clutch torque M.sub.K refers to the maximum permissible frictional performance for a clutch. In a further embodiment the lowest range begins at a rotation speed difference Δn of 0. The highest range ends - as described in the first embodiment - at the set-point rotation speed difference Δn.sub.SOLL.

[0070] According to a further embodiment the number of ranges into which the set-point rotation speed difference Δn.sub.SOLL is divided, is smaller than or equal to a number of clutches that can be actuated separately in order to reach the specified set-point rotation speed difference Δn.sub.SOLL. Thus, in the first embodiment two controllable clutches 32, 34 can be actuated over a range Δn.sub.2. According to a further embodiment three controllable clutches can be actuated over two ranges. In another embodiment, with n ranges the number of clutches is smaller than or equal to n.

[0071] According to a further embodiment the actual rotation speed difference Δn.sub.IST is increased from the first range Δn.sub.1 to the last or n-th range An.sub.n, which is limited by the set-point rotation speed difference Δn.sub.SOLL, by correspondingly actuating an increasing number of separately controllable clutches in the closing direction in order to reach the specified set-point rotation speed difference Δn.sub.SOLL. In a further embodiment, in at least two adjacent ranges the same number of clutches are actuated. According to another embodiment the respective clutches are actuated differently so that they individually produce a different clutch torque MK, in such manner that the sum of the clutch torques M.sub.K of the clutches actuated in the said range remains the same or increases from one range to the next-higher adjacent range. According to further embodiments, when there are two ranges Δn.sub.1, Δn.sub.2, in the first range Δn.sub.1 one clutch 32 is actuated and in the second range Δn.sub.2 two clutches 32, 34 - as described in the first embodiment - or alternatively three or more clutches are actuated to close. In another embodiment, when there are two ranges two controllable clutches can be actuated to close, and in the second range three or more clutches can be actuated to close.

[0072] According to a further embodiment, in at least one of the ranges each of the clutches that can be actuated in order to reach the specified set-point rotation speed difference Δn.sub.SOLL is actuated to close. In further embodiments all these ranges are at least the last two ranges or the last range. According to a further embodiment, with two ranges and two clutches that can be actuated to close in the second range, both of the controllable clutches are closed. In a further embodiment, with two ranges and three clutches that can be actuated to close, in the second range all three of the controllable clutches can be closed.

[0073] According to a further embodiment, at least in the range closest to the set-point rotation speed difference Δn.sub.SOLL, each of the clutches that can be actuated in order to reach the specified set-point rotation speed difference Δn.sub.SOLL is actuated to close. This range is also called the last or the n-th range. With a total of two ranges Δn.sub.1, Δn.sub.2, this range Δn.sub.n then corresponds to the second range Δn.sub.2. With a total of three ranges the said range then corresponds to the third range, etc.

[0074] In a further embodiment, at least in the range which is farthest away from the set-point rotation speed difference Δn.sub.SOLL, one clutch 32 of those clutches which can be actuated in order to reach the specified set-point rotation speed difference Δn.sub.SOLL is actuated to close. This range is also called the first range Δn.sub.1. According to a further embodiment, the said clutch 32 has the lowest or the highest maximum clutch torque M.sub.K, i.e. the lowest or the highest maximum frictional performance of all the clutches that can be actuated to close.

[0075] According to a further embodiment the hydrodynamic torque converter comprises a guide wheel.

[0076] In a further embodiment, the hydrodynamic torque converter is connected by way of the pump wheel on its input side, directly or indirectly, for example via a further gear system, to the drive device for propelling the vehicle.

[0077] According to a further embodiment, the adjustment (S3.3) of the actual rotation speed difference Δn.sub.IST to the set-point rotation speed difference Δn.sub.SOLL takes place in that at least one of the clutches, for example at least the first/earliest actuated clutch or at least the last/most-recently actuated clutch, is actuated to close or to open, until the set-point rotation speed difference Δn.sub.SOLL is maintained over a defined time period and within a defined tolerance range.

[0078] Thus, the invention provides for a division of the clutch torque M.sub.K required in order to reach a set-point rotation speed difference Δn.sub.SOLL between at least two clutches. In that way, instead of actuating a single clutch up to its maximum frictional performance, the frictional performance can be divided between two or more clutches, which increases the life of the individual clutches and enables a lastingly reliable calibration of the converter lock-up clutch 22.

TABLE-US-00001 Indexes 10 Transmission device 12 Control unit 14 Hydrodynamic torque converter 16 Transmission 18 Pump wheel 20 Turbine wheel 22 Converter lock-up clutch 24 Signal input 26 Shaft assembly 28 Shaft assembly 30 Shaft assembly 32 Clutch (KV in the shaft assembly 26) 34 Clutch (KR in the shaft assembly 28) 36 Clutch (K4 in the shaft assembly 30) 38 Signal output 40 Computer unit M.sub.K Clutch torque n.sub.IST-P Actual rotation speed (of the pump wheel 18) n.sub.IST-T Actual rotation speed (of the turbine wheel 20) n Rotation speed Δn Rotation speed difference Δn.sub.IST Actual rotation speed difference Δn.sub.SOLL Set-point rotation speed difference Δn.sub.1, First range (of the set-point rotation speed difference Δn.sub.SOLL) Δn.sub.2 Second range (of the set-point rotation speed difference Δn.sub.SOLL) Δn.sub.n Last/n-th range (of the set-point rotation speed difference Δnso.sub.LL) to Time-point (start) t.sub.1 Time-point (0 ≤ Δn < ½Δn.sub.SOLL t.sub.2 Time-point (Δn = ½Δn.sub.SOLL) t.sub.3 Time-point (Δn ≈ Δn.sub.SOLL) t.sub.4 Time-point (Δn = Δn.sub.SOLL)